The possibility of plant growth depends on different environmental factors such as temperature, humidity, and concentrations of salts in soil. In some cases, an environment characterized by such factors is suitable for a certain plant but not for other plants. In general, the above factors that would influence plant growth are referred to as environmental stresses. Cases in which a given plant cannot grow or is fatally damaged in an environment characterized by certain environmental stresses are explained by noting that the plant lacks environmental stress resistance. On the other hand, cases in which a plant that can grow in an environment characterized by certain environmental stresses are explained by noting that such plant has environmental stress resistance.
Plants are cultivated for the purpose of using some tissues thereof (e.g., seeds, roots, leaves, or stems) or for the purpose of producing various materials, such as fats and oils. Examples of fats and oils produced from plants that have been heretofore known include soybean oil, sesame oil, olive oil, coconut oil, rice oil, cottonseed oil, sunflower oil, corn oil, safflower oil, palm oil, and rapeseed oil. Such fats and oils are extensively used for household and industrial applications. Also, fats and oils produced from plants are used as raw materials for biodiesel fuel or bioplastic, and the applicability thereof is increasing for alternative energy to petroleum.
If environmental stress resistance can be imparted to a plant, it becomes possible to expand the area in which the plant can grow, allowing the effective use of limited ground space. In particular, an energy crop such as sugarcane is used as a material for biofuel. Therefore, it desirable for such energy crop to gain resistance to a variety of environmental stresses. That is to say, if environmental stress resistance can be imparted to the above energy crop, the energy crop can be cultivated in an area in which the crop cannot be cultivated due to the above described environmental factors. Techniques for imparting environmental stress resistance to plants are described in Patent Documents 1 and 2 and Non-Patent Document 1. Patent Document 1 discloses a method for imparting salt stress resistance to a plant by introducing a gene involved in the synthesis of glycine betaine serving as an osmolyte to the plant. Both Patent Document 2 and Non-Patent Document 1 disclose a method for imparting environmental stress resistance to a plant by introducing a gene encoding a tobacco-derived receptor-like protein into the plant.
In addition, in Patent Document 2 and Non-Patent Document 1, a gene encoding a receptor-like protein is introduced. However, these documents do not disclose examples of gene introduction with the use of a gene encoding a receptor-like protein having a leucine-rich repeat structure or a gene encoding a receptor-like protein kinase having a leucine-rich repeat structure. Further, Non-Patent Documents 2 and 3 report that a receptor-like protein kinase having a leucine-rich repeat structure plays an important role in the reaction to stress.